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From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 3/9] arm64: mm: Permit transitioning from Global to Non-Global without BBM
Date: Mon, 29 Jan 2018 11:59:54 +0000	[thread overview]
Message-ID: <1517227200-20412-4-git-send-email-will.deacon@arm.com> (raw)
In-Reply-To: <1517227200-20412-1-git-send-email-will.deacon@arm.com>

Break-before-make is not needed when transitioning from Global to
Non-Global mappings, provided that the contiguous hint is not being used.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm64/mm/mmu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index b44992ec9643..fc7902bda02b 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -118,6 +118,10 @@ static bool pgattr_change_is_safe(u64 old, u64 new)
 	if ((old | new) & PTE_CONT)
 		return false;
 
+	/* Transitioning from Global to Non-Global is safe */
+	if (((old ^ new) == PTE_NG) && (new & PTE_NG))
+		return true;
+
 	return ((old ^ new) & ~mask) == 0;
 }
 
-- 
2.1.4

  parent reply	other threads:[~2018-01-29 11:59 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-29 11:59 [PATCH v2 0/9] Fix kpti-enabled kernels for Cavium ThunderX Will Deacon
2018-01-29 11:59 ` [PATCH v2 1/9] arm64: Add software workaround for Falkor erratum 1041 Will Deacon
2018-01-29 11:59 ` [PATCH v2 2/9] arm64: kpti: Make use of nG dependent on arm64_kernel_unmapped_at_el0() Will Deacon
2018-01-29 11:59 ` Will Deacon [this message]
2018-01-29 11:59 ` [PATCH v2 4/9] arm64: kpti: Add ->enable callback to remap swapper using nG mappings Will Deacon
2018-01-30 10:30   ` Will Deacon
2018-01-29 11:59 ` [PATCH v2 5/9] arm64: Force KPTI to be disabled on Cavium ThunderX Will Deacon
2018-01-29 11:59 ` [PATCH v2 6/9] arm64: assembler: Change order of macro arguments in phys_to_ttbr Will Deacon
2018-01-29 11:59 ` [PATCH v2 7/9] arm64: entry: Reword comment about post_ttbr_update_workaround Will Deacon
2018-02-03 11:15   ` Ard Biesheuvel
2018-02-05 16:41     ` Will Deacon
2018-01-29 11:59 ` [PATCH v2 8/9] arm64: assembler: Align phys_to_pte with pte_to_phys Will Deacon
2018-01-29 12:00 ` [PATCH v2 9/9] arm64: idmap: Use "awx" flags for .idmap.text .pushsection directives Will Deacon
2018-02-03 11:36 ` [PATCH v2 0/9] Fix kpti-enabled kernels for Cavium ThunderX Ard Biesheuvel
2018-02-05 16:41   ` Will Deacon
2018-02-05 19:21     ` Ard Biesheuvel
2018-02-06 22:31 ` Catalin Marinas

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